U.S. patent number 7,217,311 [Application Number 10/799,923] was granted by the patent office on 2007-05-15 for method of producing metal nanocomposite powder reinforced with carbon nanotubes and the power prepared thereby.
This patent grant is currently assigned to Korea Advanced Institute of Science and Technology. Invention is credited to Seung Il Cha, Seong Hyun Hong, Soon Hyung Hong, Kyung Tae Kim.
United States Patent |
7,217,311 |
Hong , et al. |
May 15, 2007 |
Method of producing metal nanocomposite powder reinforced with
carbon nanotubes and the power prepared thereby
Abstract
The present invention relates to a metal nanocomposite powder
reinforced with carbon nanotubes and to a process of producing a
metal nanocomposite powder homogeneously reinforced with carbon
nanotubes in a metal matrix powder.
Inventors: |
Hong; Soon Hyung (Daejeon,
KR), Cha; Seung Il (Daejeon, KR), Kim;
Kyung Tae (Daejeon, KR), Hong; Seong Hyun
(Daejeon, KR) |
Assignee: |
Korea Advanced Institute of Science
and Technology (Daejeon, KR)
|
Family
ID: |
34617191 |
Appl.
No.: |
10/799,923 |
Filed: |
March 15, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070074601 A1 |
Apr 5, 2007 |
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Foreign Application Priority Data
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Jul 25, 2003 [KR] |
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10-2003-0051549 |
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Current U.S.
Class: |
75/345;
75/365 |
Current CPC
Class: |
C09C
1/56 (20130101); B22F 1/0059 (20130101); B01J
6/001 (20130101); C09C 1/48 (20130101); B01J
19/10 (20130101); B82Y 30/00 (20130101); C01P
2004/03 (20130101); B22F 2998/10 (20130101); B22F
2999/00 (20130101); C01P 2004/13 (20130101); B22F
2998/00 (20130101); C01P 2002/72 (20130101); B22F
2999/00 (20130101); B22F 9/22 (20130101); B22F
2201/013 (20130101); B22F 2201/04 (20130101); B22F
2998/10 (20130101); C01B 32/05 (20170801); B01J
6/001 (20130101); B01J 19/10 (20130101); B22F
9/22 (20130101); B22F 2998/00 (20130101); C22C
26/00 (20130101); C22C 2026/002 (20130101) |
Current International
Class: |
B22F
9/20 (20060101) |
Field of
Search: |
;75/345,365,371 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Bian, Z. et al., "Excellent Wave Absorption by Zirconium-Based Bulk
Metallic Glass Composites Containing Carbon Nanotubes", Advanced
Materials, vol. 15, No. 7-8, Apr. 17,2003, pp. 616-621. cited by
examiner .
Bian, Z. et al., "Excellent ultrasonic Absorption Ability of
Carbon-Nanotube-Reinforced Bulk Metallic Glass Composites", Applied
Physics Letters, vol. 82, No. 17, Apr. 28, 2003, pp. 2790-2792.
cited by examiner .
Chen, X. et al., "Carbon Nanotube omposite Deposits with High
Hardness and High Wear Resistance", Advanced Engineering Materials,
vol. 5, No. 7, May 7, 2003, pp. 514-518. cited by examiner .
Dong, S.R., et al., "An investigation of the sliding wear behavior
of Cu-matrix composite reinforced by carbon nanotubes," Mater. Sci.
Eng. A313:83-87, Elsevier Science B.V. (2001). cited by other .
Flahaut, E., et al., "Carbon Nanotube-Metal-Oxide Nanocomposites:
Microstructure, Electrical Conductivity and Mechanical
Properities," Acta Mater. 48: 3803-3812, Pergamon Press (2000).
cited by other .
Xu, C.L., et al., "Fabrication of aluminum-carbon nanotube
composites and their electrical properties," Carbon 37:855-858,
Pergamon Press (1999). cited by other .
Laurent, C., et al., "Carbon Nanotubes-Fe-Alumina Nanocomposites.
Part II: Microstructure and Mechanical Properties of the
Hot-Pressed Composites," J. Eur. Ceram. Soc. 18:2005-2013, Elsevier
Science Ltd. (1998). cited by other .
Peigney, A., et al., "Carbon nanotubes in novel ceramic matrix
nanocomposites," Ceram. Int. 26:677-683, Elsevier Science Ltd.
(2000). cited by other .
Siegel, R.W., et al., "Mechanical behavior of polymer and ceramic
matrix nanocomposites," Scripta Mater. 44:2061-2064, Elsevier
Science Ltd. (2001). cited by other .
Hwang, G.L. et al., "Carbon nanotube reinforced ceramics," J.
Mater. Chem., 11:1722-1725 The Royal Society of Chemistry (2001).
cited by other .
Ning, J., et al., "Fabrication and mechanical properties of
SiO.sub.2 matrix composites reinforced by carbon nanotube," Mater.
Sci. Eng. A357:392-396 Elsevier Science B.V. (2003). cited by other
.
Ning, J., et al., "Fabrication and thermal property of carbon
nanotube/SiO.sub.2 composites," J. Mater. Sci. Let. 22:1019-1021
Kluwer Academic Publishers (2003). cited by other.
|
Primary Examiner: Wyszomierski; George
Attorney, Agent or Firm: Sterne, Kessler, Goldstein &
Fox P.L.L.C.
Claims
What is claimed is:
1. A method of producing a metal nanocomposite powder in which
carbon nanotubes are dispersed in a matrix, the method comprising:
(a) dispersing carbon nanotubes in a predetermined dispersing
solvent to form a dispersed solution; (b) primarily treating the
dispersed solution using ultrasonic waves; (c) uniformly mixing
water-soluble metal salts or metal hydrates with the treated
dispersed solution of (b); (d) secondarily treating the dispersed
solution of (c) using ultrasonic waves; (e) drying and calcining
the dispersed solution of (d) to produce a metal oxide
nanocomposite powder; and (f) reducing the metal oxide
nanocomposite powder of (e).
2. The method of claim 1, wherein the dispersing solvent of (a) is
selected from the group consisting of water, ethanol, nitric acid
solution, toluene, N,N-dimethylformamide, dichlorocarbene, and
thionyl chloride.
3. The method of claim 1, wherein the water-soluble metal salts or
metal hydrates of (c) comprise a metal selected from the group
consisting of copper, nickel, cobalt, iron, and tungsten.
4. The method of claim 1, wherein the drying of (e) is conducted at
about 80.degree. C. to about 100.degree. C.
5. The method of claim 1, wherein the calcining of (e) is conducted
at about 200.degree. C. to about 350.degree. C. under atmospheric
air.
6. The method of claim 1, wherein the calcining of (e) is conducted
at about 400.degree. C. to about 1700.degree. C. under reduced
pressure.
7. The method of claim 6, further comprising a drying step at about
300.degree. C. to about 350.degree. C.
8. The method of claim 1, wherein the reducing of (f) is conducted
under a reducing gas atmosphere.
9. The method of claim 1, wherein the reducing of (f) is conducted
under a hydrogen, CO, or CO.sub.2 gas atmosphere.
Description
This application claims priority to Korean Patent Application No.
10-2003-0051549, filed Jul. 25, 2003, which is incorporated by
reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal nanocomposite powder
reinforced with carbon nanotubes and to a process of producing a
metal nanocomposite powder homogeneously reinforced with carbon
nanotubes in a metal matrix powder.
2. Related Art
In order to fabricate carbon nanotube-reinforced composites, many
studies have focused on a powder--powder blending between carbon
nanotubes and raw metal or ceramic powder. For example, B. Q. Wei
(Wei, B. Q. et al., Carbon 37:855 858 (1999)), and S. R. Dong
(Dong, S. R. et al., Materials Science and Engineering, A313:83 87
(2001)), suggest an aluminum or copper matrix composite material
reinforced with carbon nanotubes, which is synthesized using a
powder mixing process and a conventional sintering process.
However, characterization of these carbon nanotube-reinforced
composite materials show low enhancement, or even a decrease, of
mechanical properties. In particular, the relative density of the
sintered composite materials is very low, ranging from 85% to 95%.
The relative density of composites is important since low relative
density means the existence of many fracture sources, such as pores
and defects, which can originate from low mechanical properties.
There are two reasons for these problems. One comes from the severe
agglomeration of carbon nanotubes in a metal matrix. The other is
the use of conventional consolidation processes. The present
invention mainly focuses on a solution to prevent agglomeration of
carbon nanotubes in a metal matrix. In order to homogeneously
disperse carbon nanotubes in a metal matrix, metal nanocomposite
powders homogeneously reinforced with carbon nanotubes are
fabricated. Even though the conventional process for producing
carbon nanotube reinforced metal matrix composites contains a
fabrication process, e.g. ball milling, for homogeneous blending of
carbon nanotubes and metal powder, this process is not an effective
method of dispersing carbon nanotubes. Therefore, the present
invention proposes a new metal nanocomposite powder homogeneously
reinforced with carbon nanotube in a metal matrix and a new method
for producing these powders.
Previously, the blending of the carbon nanotubes and metal or
ceramic powders did not yield satisfactory results. This is due to
difficulty in homogeneously dispersing carbon nanotubes in a metal
matrix by simple ball milling processes. Composite powder
fabricated by conventional processes show severe agglomeration of
carbon nanotubes, especially on the surface of metal powder, and
the nanotubes are not homogeneously dispersed inside the metal
matrix. The agglomeration of carbon nanotubes on the surface of the
metal powder prevents metal matrix powder from being sintered
during consolidation, since aggregates on the surface of metal
powder can interrupt the diffusion pathway of metal atoms between
metal powders. This leads not only to low sinterability of matrix
materials including the carbon nanotubes but also to low relative
density of composite materials. That is to say, after the
consolidation process, the agglomerated carbon nanotubes become
pores in the composite material.
FIGS. 1A and 1B contain scanning electron micrograph (SEM) pictures
showing the surface structure of a conventional composite powder.
These figures demonstrate that a simple mixing and dispersing
process, such as a ball milling process, does not prevent the
carbon nanotubes from being agglomerated and does not provide a
uniform mixing of carbon nanotubes with the matrix powder. In other
words, it is impossible to produce a sound metal composite powder
or material through a conventional mixing or dispersing process.
The term "sound" as used herein means that the carbon nanotubes are
not agglomerated on a surface of the metal powder, but rather are
homogeneously dispersed in the metal powder.
SUMMARY OF THE INVENTION
The present invention is directed to a method of producing a metal
nanocomposite powder homogeneously reinforced with carbon nanotubes
in a metal matrix without being agglomerated.
The present invention is directed to a method of producing a metal
nanocomposite powder in which carbon nanotubes are dispersed in a
matrix, the method comprising (a) dispersing carbon nanotubes in a
predetermined dispersing solvent to form a dispersed solution, (b)
primarily treating the dispersed solution using ultrasonic waves,
(c) uniformly mixing water-soluble metal salts or metal hydrates
with the treated dispersed solution of (b), (d) secondarily
treating the dispersed solution of (c) using ultrasonic waves, (e)
drying and calcining the dispersed solution of (d) to produce a
metal oxide nanocomposite powder, and (f) reducing the metal oxide
nanocomposite powder of (e).
Metal nanocomposite powder produced according to the method of the
present invention, in which the carbon nanotubes are dispersed in
the metal matrix powder, is illustrated in FIGS. 2A and 2B. FIG. 2A
illustrates a carbon nanotube/metal nanocomposite powder, in which
the carbon nanotubes intersect grain boundaries. FIG. 2B
illustrates a carbon nanotube/metal nanocomposite powder, in which
small carbon nanotube agglomerates intersect the grain boundaries
in a metal matrix powder.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a scanning electron microscope (SEM) picture of a
conventional metal composite powder, in which carbon nanotubes are
agglomerated on a surface of a metal.
FIG. 1B is a highly magnified view of FIG. 1A.
FIG. 2A illustrates a carbon nanotube/metal nanocomposite powder
according to the present invention, in which carbon nanotubes
intersect grain boundaries.
FIG. 2B illustrates another carbon nanotube/metal nanocomposite
powder according to the present invention, in which carbon nanotube
agglomerates intersect grain boundaries.
FIG. 3 is a flow chart illustrating the fabrication of the carbon
nanotube/metal nanocomposite powder according to the present
invention.
FIG. 4A is a SEM picture showing a surface structure of a carbon
nanotube/copper oxide nanocomposite powder after the calcination
process of the present invention.
FIG. 4B illustrates qualitative analysis results of carbon
nanotube/copper oxide nanocomposite powder after the calcination
process of the present invention by use of an X-ray diffractometer
(XRD).
FIG. 5 schematically illustrates a reducing gas furnace used in the
present invention.
FIG. 6A is a SEM picture showing a surface structure of a carbon
nanotube/copper nanocomposite powder after the reduction process of
the present invention.
FIG. 6B illustrates qualitative analysis results of carbon
nanotube/copper nanocomposite powder after the reduction process of
the present invention by use of XRD.
DETAILED DESCRIPTION
The present invention is directed to a method of producing a metal
nanocomposite powder in which carbon nanotubes are dispersed in a
matrix, the method comprising (a) dispersing carbon nanotubes in a
predetermined dispersing solvent to form a dispersed solution, (b)
primarily treating the dispersed solution using ultrasonic waves,
(c) uniformly mixing water-soluble metal salts or metal hydrates
with the treated dispersed solution of (b), (d) secondarily
treating the dispersed solution of (c) using ultrasonic waves, (e)
drying and calcining the dispersed solution of (d) to produce a
metal oxide nanocomposite powder, and (f) reducing the metal oxide
nanocomposite powder of (e).
Generally, a carbon nanotube has the strength of 30 GPa and elastic
modulus of 1 TPa. The carbon nanotube useful in the present
invention is not specifically limited, but it is preferable that
its aspect ratio is relatively high. In some embodiments, the
aspect ratio of the carbon nanotube is about 10 to about 10,000.
Additionally, in some embodiments carbon nanotubes with high
purity, i.e., 95% or higher, are used. The carbon nanotube of the
present invention can be tube shaped, having a diameter of about 10
nm to about 40 nm and a length of about 5 .mu.m, and is added as a
reinforcing material into a metal composite material.
A dispersing solvent plays a role in dispersing a bundle of carbon
nanotubes into separate carbon nanotubes. Any kind of dispersing
solvents can be used in the present invention as long as the
dispersing solvent functionalizes the carbon nanotube; that is to
say, functional groups are formed on the carbon nanotube by the
dispersing solvent. Examples of dispersing solvents include, but
are not limited to, water, ethanol, nitric acid solution, toluene,
N,N-dimethylformamide, dichlorocarbene, and thionyl chloride.
Water, ethanol, and nitric acid solution each have simple solution
characteristics, and realize an electrostatic charge on the surface
of the carbon nanotube and the carboxylation of the carbon
nanotube, thereby contributing to even dispersement of the carbon
nanotube in the dispersing solvent.
A primary ultrasonic treatment is conducted to promote uniform
dispersion of the carbon nanotube in the dispersing solvent. In
some embodiments, the range of ultrasonic waves is about 40 KHz to
about 60 KHz. In some embodiments, the primary ultrasonic treatment
can be conducted for about two hours to about ten hours. Any
traditional ultrasonic cleaning device can be used within the
described range, e.g., Model 08893-16 (Cole-Parmer Co., Vernon
Hills, Ill.).
Any metal materials forming water-soluble metal salts or metal
hydrates can be used as the metal matrix material of the carbon
nanotube/metal nanocomposite powder. In some embodiments, the metal
matrix material useful in the present invention can be, but is not
limited to, copper, nickel, cobalt, iron, or tungsten.
After adding the water-soluble metal salts or metal hydrates into
the dispersing solvent in which carbon nanotubes are already
dispersed, a secondary ultrasonic treatment can be conducted under
the same conditions as the primary ultrasonic treatment. In some
embodiments, the secondary ultrasonic treatment can be conducted
for about ten hours or less using ultrasonic waves of about 40 KHz
to about 60 KHz. A secondary ultrasonic treatment for more than
about ten hours can cause surface defects on the carbon nanotubes,
thus a graphite structure arranged on the surface of the carbon
nanotubes can be destroyed. The ultrasonic treatment serves to
evenly disperse the carbon nanotubes and water-soluble salts in the
dispersing solvent and induce formation of a chemical bond between
molecules of the carbon nanotubes and the water-soluble salts.
In some embodiments, drying and calcination are conducted under
various conditions, e.g., under a vacuum, a hydrogen gas
atmosphere, an argon gas atmosphere, or an inert gas (nitrogen or
any atmosphere where the carbon nanotube is not damaged).
Conditions for calcination can be changed according to the kind of
metal matrix desired.
The carbon nanotube is apt to be rapidly oxidized and destroyed at
about 400.degree. C. or higher in atmospheric air. Accordingly, in
some embodiments the drying process is conducted at about
80.degree. C. to about 100.degree. C. so as to sufficiently remove
moisture from the dispersing solvent. In some embodiments, the
drying process is conducted at such temperature for about 6 hours
to about 12 hours, so as to sufficiently supply oxygen and air to a
composite powder. A drying process under these conditions removes
moisture and any organic solvents from the composite powder.
Conditions for calcination depend on the kind of metal matrix used.
For example, if the metal matrix requires a calcination temperature
of about 400.degree. C. or lower, the carbon nanotube can be
calcined at about 200.degree. C. to about 350.degree. C. under
atmospheric air to prevent the carbon nanotube from being damaged.
In this regard, impurities, such as organic solvents contained in
the composite powder, are removed and oxides are formed on the
composite powder at about 350.degree. C. or lower. If the
calcination temperature is lower than about 200.degree. C., the
organic solvent is insufficiently removed from the composite
powder. The calcination process can be conducted for about one hour
to about four hours so as to form stable oxides. On the other hand,
when the metal matrix requires a calcination temperature of about
400.degree. C. or higher, calcination can be conducted under a
reduced pressure (e.g., about 10.sup.-1 torr) so as to prevent the
carbon nanotubes from being exposed to high temperatures and air,
which leads to damage, and can be conducted at a temperature range
of about 400.degree. C. to about 1700.degree. C. so as to produce
stable oxides. When the calcination is conducted at about
1700.degree. C. or higher, the carbon nanotubes can be easily
damaged by oxygen even though oxygen exists at low concentration
under the reduced pressure. Hence, in some embodiments the
calcination is conducted at about 1700.degree. C. or lower when the
metal matrix requires a calcination temperature of about
400.degree. C. or higher. In some embodiments, the metal
nanocomposite powder is dried at about 80.degree. C. to about
100.degree. C. for about 6 to about 12 hours and then again dried
at about 300.degree. C. to about 350.degree. C. for about 6 to
about 12 hours to sufficiently provide air throughout the composite
powder to form the stable oxides at the reduced pressure.
In Example 1, the composite powder is produced using copper oxide
as the metal matrix, the copper oxide requiring a calcination
temperature of about 400.degree. C. or lower.
The drying process functions to remove hydrogen, water vapor and
nitrogen from the composite powder. The calcination process
contributes to producing a stable carbon nanotube/metal oxide
nanocomposite powder.
The calcined carbon nanotube/metal oxide nanocomposite powder is
reduced to separate oxygen from metal oxide in the carbon
nanotube/metal oxide nanocomposite powder. FIG. 5 illustrates a
furnace for a reduction process. In some embodiments the reduction
process is conducted at about 100.degree. C. to about 1000.degree.
C. under a reducing gas, such as CO, CO.sub.2, or hydrogen
atmosphere. Hydrogen gas is useful to prevent the carbon nanotube
from being damaged and to convert the metal oxide into a metal
without affecting the carbon nanotube since hydrogen easily bonds
to oxygen. Further, hydrogen gas can be used in reduction processes
conducted at relatively wide temperature ranges of about
100.degree. C. to about 1000.degree. C. and for a relatively long
time of from about one hour to about ten hours. However, since
hydrogen easily reacts with oxygen, causing an explosion, and since
oxygen significantly affects the oxidation of carbon nanotubes,
oxygen should not exist in the furnace. The absence of oxygen
allows heat treatment of the composite powder at relatively high
temperatures under a hydrogen atmosphere. Furthermore, in some
embodiments CO and CO.sub.2 are not used at about 500.degree. C. or
higher to prevent the oxidation of the carbon nanotube because the
carbon nanotube is easily damaged by oxygen even though CO or
CO.sub.2 is used instead of hydrogen. CO or CO.sub.2 is cautiously
used at about 500.degree. C. or lower.
Some variables, such as the reduction temperature and a flow rate
of the reducing gas, are determined through experimentation and are
dependent on the metal matrix used.
FIG. 3 illustrates a flow chart depicting the production of a metal
nanocomposite powder reinforced with carbon nanotubes according to
the present invention. Example 1 provides a detailed description of
the production of the metal nanocomposite powder reinforced with
the carbon nanotube as shown in FIG. 3. In this example, a
water-soluble copper salt is used to adopt copper powder as the
metal matrix. It is understood that modifications of a metal matrix
will be apparent to those skilled in the art without departing from
the spirit of the invention.
A better understanding of the present invention can be obtained in
light of the following example which is set forth to illustrate,
but is not to be construed to limit, the present invention.
EXAMPLE 1
A carbon nanotube/copper nanocomposite powder calcined at
400.degree. C. or lower was provided. The procedure used to produce
the carbon nanotube/copper nanocomposite powder was as follows. 20
mg of multi-wall carbon nanotube (Nanotech Co. Ltd., Korea)
(diameter: about 10 to about 40 nm; length: 5 .mu.m) was added into
300 ml of ethanol acting as a dispersing solvent. The resulting
solution was treated using ultrasonic waves of 50 W and 45 KHz
generated from an ultrasonic cleaning device (Model 08893-16,
Cole-Parmer Co., Vernon Hills, Ill.) for two hours to produce a
dispersion solution in which carbon nanotubes were evenly dispersed
in an ethanol solution.
3 g of copper salt (Cu(CH.sub.3COO).sub.2) was added into the
dispersion solution to allow the voluminal percentage of carbon
nanotubes in the dispersion solution to be 10% (by volume). The
resulting dispersion solution was again treated using ultrasonic
waves of 50 W and 45 KHz for two hours, thereby evenly dispersing
the carbon nanotube and copper molecules in the dispersion solution
and inducing the chemical bond between molecules of the carbon
nanotube and copper.
The dispersion solution treated using the ultrasonic wave was
heated at about 80.degree. C. to 100.degree. C. for eight hours to
remove water from the dispersion solution, and calcined at
300.degree. C. to 350.degree. C. for four hours under normal
atmosphere, thereby removing needless organic solvent from the
dispersion solution and sufficiently providing oxygen to the
dispersion solution to form the stable oxide (see FIGS. 4A and
4B).
After the calcination, reduction was conducted in a furnace as
shown in FIG. 5. The reduction was conducted at 200.degree. C. for
two hours under a hydrogen gas atmosphere.
The analysis of reduced powder was performed using an XRD to
confirm a kind and a phase state of the reduced powder. The results
shown in FIG. 6A confirm that a carbon nanotube/copper
nanocomposite powder was obtained.
Furthermore, the analysis of the reduced powder by a SEM, as shown
in FIG. 6B, confirmed that a surface state of the reduced powder
was the same as that of the carbon nanotube/copper nanocomposite
powder; the morphology of the reduced powder was greatly improved
in comparison with conventional composite powder. Additionally, as
described in Table 1, an initially estimated voluminal percentage
of the carbon nanotube in the carbon nanotube/copper nanocomposite
powder was the same as a measured voluminal percentage of the
carbon nanotube in the carbon nanotube/copper nanocomposite powder.
This implies that the voluminal percentage of carbon nanotubes can
be easily determined when a composite material powder is
produced.
TABLE-US-00001 TABLE 1 Volume percentage of the carbon nanotube
contained in the carbon nanotube/copper nanocomposite powder
Initially estimated volume percentage of carbon nanotube in carbon
nanotube/copper nanocomposite powder Weight Volume Added Copper
percentage percentage Carbon copper in copper of carbon of carbon
nanotube acetates acetates nanotube nanotube (g) (g) (g) (wt %)
(vol %) 0.02 3 0.95 2.5 10 Measured volume percentage of carbon
nanotube in carbon nanotube/copper nanocomposite powder Measured
weight percentage of carbon Volume percentage (wt %) (vol %) Copper
oxide powder after 2.3 10 calcination Copper powder after 2.3 10
reduction
As described herein, the present invention provides a metal
nanocomposite powder reinforced with carbon nanotubes, in which the
carbon nanotubes are evenly dispersed in a metal matrix, thereby
avoiding the agglomeration of carbon nanotubes, which is a problem
of conventional composite powders and materials containing carbon
nanotubes. Therefore, installation costs of a device for producing
the metal nanocomposite powder of the present invention are
reduced, production processing of the metal nanocomposite powder is
simplified, and mass production of the metal nanocomposite powder
becomes feasible.
Conventional studies of carbon nanotubes have focused on an
electronic element field for the dispersion, basical
functionalization, and alignment of carbon nanotubes. However, the
present invention provides a base technology for the production of
a metal nanocomposite material including carbon nanotubes.
Accordingly, metal nanocomposite powders can be used as high-valued
abrasive materials or wear-resistant coating materials.
Furthermore, the metal nanocomposite powder of the present
invention can be applied to industrial fields which utilize
conventional metal composite materials, such as the aerospace,
high-performance machine parts, and medical industry, because it
has high sintering performance and easily becomes bulky.
This example illustrates one possible method of the present
invention. While the invention has been particularly shown and
described with reference to some embodiments thereof, it will be
understood by those skilled in the art that they have been
presented by way of example only, and not limitation, and various
changes in form and details can be made therein without departing
from the spirit and scope of the invention. Thus, the breadth and
scope of the present invention should not be limited by any of the
above-described exemplary embodiments, but should be defined only
in accordance with the following claims and their equivalents.
All documents cited herein, including journal articles or
abstracts, published or corresponding U.S. or foreign patent
applications, issued or foreign patents, or any other documents,
are each entirely incorporated by reference herein, including all
data, tables, figures, and text presented in the cited
documents.
* * * * *